suricata/src/detect-isdataat.c

/* Copyright (C) 2007-2010 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

/**
 * \file
 *
 * \author Pablo Rincon <pablo.rincon.crespo@gmail.com>
 *
 * Implements isdataat keyword
 */

#include "suricata-common.h"
#include "debug.h"
#include "decode.h"
#include "detect.h"
#include "detect-engine.h"
#include "detect-parse.h"
#include "app-layer.h"

#include "util-unittest.h"
#include "util-unittest-helper.h"

#include "detect-isdataat.h"
#include "detect-content.h"
#include "detect-uricontent.h"

#include "flow.h"
#include "flow-var.h"

#include "util-debug.h"
#include "util-byte.h"
#include "detect-pcre.h"
#include "detect-bytejump.h"
#include "detect-byte-extract.h"

/**
 * \brief Regex for parsing our isdataat options
 */
#define PARSE_REGEX  "^\\s*!?([^\\s,]+)\\s*(,\\s*relative)?\\s*(,\\s*rawbytes\\s*)?\\s*$"

static pcre *parse_regex;
static pcre_extra *parse_regex_study;

int DetectIsdataatSetup (DetectEngineCtx *, Signature *, char *);
void DetectIsdataatRegisterTests(void);
void DetectIsdataatFree(void *);

/**
 * \brief Registration function for isdataat: keyword
 */
void DetectIsdataatRegister(void)
{
    sigmatch_table[DETECT_ISDATAAT].name = "isdataat";
    sigmatch_table[DETECT_ISDATAAT].desc = "check if there is still data at a specific part of the payload";
    sigmatch_table[DETECT_ISDATAAT].url = DOC_URL DOC_VERSION "/rules/payload-keywords.html#isadataat";
    /* match is handled in DetectEngineContentInspection() */
    sigmatch_table[DETECT_ISDATAAT].Match = NULL;
    sigmatch_table[DETECT_ISDATAAT].Setup = DetectIsdataatSetup;
    sigmatch_table[DETECT_ISDATAAT].Free  = DetectIsdataatFree;
    sigmatch_table[DETECT_ISDATAAT].RegisterTests = DetectIsdataatRegisterTests;

    DetectSetupParseRegexes(PARSE_REGEX, &parse_regex, &parse_regex_study);
}

/**
 * \brief This function is used to parse isdataat options passed via isdataat: keyword
 *
 * \param isdataatstr Pointer to the user provided isdataat options
 *
 * \retval idad pointer to DetectIsdataatData on success
 * \retval NULL on failure
 */
DetectIsdataatData *DetectIsdataatParse (char *isdataatstr, char **offset)
{
    DetectIsdataatData *idad = NULL;
    char *args[3] = {NULL,NULL,NULL};
#define MAX_SUBSTRINGS 30
    int ret = 0, res = 0;
    int ov[MAX_SUBSTRINGS];
    int i=0;

    ret = pcre_exec(parse_regex, parse_regex_study, isdataatstr, strlen(isdataatstr), 0, 0, ov, MAX_SUBSTRINGS);
    if (ret < 1 || ret > 4) {
        SCLogError(SC_ERR_PCRE_MATCH, "pcre_exec parse error, ret %" PRId32 ", string %s", ret, isdataatstr);
        goto error;
    }

    if (ret > 1) {
        const char *str_ptr;
        res = pcre_get_substring((char *)isdataatstr, ov, MAX_SUBSTRINGS, 1, &str_ptr);
        if (res < 0) {
            SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
            goto error;
        }
        args[0] = (char *)str_ptr;


        if (ret > 2) {
            res = pcre_get_substring((char *)isdataatstr, ov, MAX_SUBSTRINGS, 2, &str_ptr);
            if (res < 0) {
                SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
                goto error;
            }
            args[1] = (char *)str_ptr;
        }
        if (ret > 3) {
            res = pcre_get_substring((char *)isdataatstr, ov, MAX_SUBSTRINGS, 3, &str_ptr);
            if (res < 0) {
                SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
                goto error;
            }
            args[2] = (char *)str_ptr;
        }

        idad = SCMalloc(sizeof(DetectIsdataatData));
        if (unlikely(idad == NULL))
            goto error;

        idad->flags = 0;
        idad->dataat = 0;

        if (args[0][0] != '-' && isalpha((unsigned char)args[0][0])) {
            if (offset == NULL) {
                SCLogError(SC_ERR_INVALID_ARGUMENT, "isdataat supplied with "
                           "var name for offset.  \"offset\" argument supplied to "
                           "this function has to be non-NULL");
                goto error;
            }
            *offset = SCStrdup(args[0]);
            if (*offset == NULL)
                goto error;
        } else {
            if (ByteExtractStringUint16(&idad->dataat, 10,
                                        strlen(args[0]), args[0]) < 0 ) {
                SCLogError(SC_ERR_INVALID_VALUE, "isdataat out of range");
                SCFree(idad);
                idad = NULL;
                goto error;
            }
        }

        if (args[1] !=NULL) {
            idad->flags |= ISDATAAT_RELATIVE;

            if(args[2] !=NULL)
                idad->flags |= ISDATAAT_RAWBYTES;
        }

        if (isdataatstr[0] == '!') {
            idad->flags |= ISDATAAT_NEGATED;
        }

        for (i = 0; i < (ret -1); i++) {
            if (args[i] != NULL)
                SCFree(args[i]);
        }

        return idad;

    }

error:
    for (i = 0; i < (ret -1) && i < 3; i++){
        if (args[i] != NULL)
            SCFree(args[i]);
    }

    if (idad != NULL)
        DetectIsdataatFree(idad);
    return NULL;

}

/**
 * \brief This function is used to add the parsed isdataatdata into the current
 *        signature.
 * \param de_ctx pointer to the Detection Engine Context
 * \param s pointer to the Current Signature
 * \param isdataatstr pointer to the user provided isdataat options
 *
 * \retval 0 on Success
 * \retval -1 on Failure
 */
int DetectIsdataatSetup (DetectEngineCtx *de_ctx, Signature *s, char *isdataatstr)
{
    SigMatch *sm = NULL;
    SigMatch *prev_pm = NULL;
    DetectIsdataatData *idad = NULL;
    char *offset = NULL;
    int ret = -1;

    idad = DetectIsdataatParse(isdataatstr, &offset);
    if (idad == NULL)
        return -1;

    int sm_list;
    if (s->init_data->list != DETECT_SM_LIST_NOTSET) {
        sm_list = s->init_data->list;

        if (idad->flags & ISDATAAT_RELATIVE) {
            prev_pm = DetectGetLastSMFromLists(s, DETECT_CONTENT, DETECT_PCRE, -1);
        }
    } else if (idad->flags & ISDATAAT_RELATIVE) {
        prev_pm = DetectGetLastSMFromLists(s,
            DETECT_CONTENT, DETECT_PCRE,
            DETECT_BYTETEST, DETECT_BYTEJUMP, DETECT_BYTE_EXTRACT,
            DETECT_ISDATAAT, -1);
        if (prev_pm == NULL)
            sm_list = DETECT_SM_LIST_PMATCH;
        else {
            sm_list = SigMatchListSMBelongsTo(s, prev_pm);
            if (sm_list < 0)
                goto end;
        }
    } else {
        sm_list = DETECT_SM_LIST_PMATCH;
    }

    if (offset != NULL) {
        SigMatch *bed_sm = DetectByteExtractRetrieveSMVar(offset, s);
        if (bed_sm == NULL) {
            SCLogError(SC_ERR_INVALID_SIGNATURE, "Unknown byte_extract var "
                       "seen in isdataat - %s\n", offset);
            goto end;
        }
        idad->dataat = ((DetectByteExtractData *)bed_sm->ctx)->local_id;
        idad->flags |= ISDATAAT_OFFSET_BE;
        SCFree(offset);
    }

    sm = SigMatchAlloc();
    if (sm == NULL)
        goto end;
    sm->type = DETECT_ISDATAAT;
    sm->ctx = (SigMatchCtx *)idad;
    SigMatchAppendSMToList(s, sm, sm_list);

    if (!(idad->flags & ISDATAAT_RELATIVE)) {
        ret = 0;
        goto end;
    }

    if (prev_pm == NULL) {
        ret = 0;
        goto end;
    }

    if (prev_pm->type == DETECT_CONTENT) {
        DetectContentData *cd = (DetectContentData *)prev_pm->ctx;
        cd->flags |= DETECT_CONTENT_RELATIVE_NEXT;
    } else if (prev_pm->type == DETECT_PCRE) {
        DetectPcreData *pd = (DetectPcreData *)prev_pm->ctx;
        pd->flags |= DETECT_PCRE_RELATIVE_NEXT;
    }

    ret = 0;

end:
    if (ret != 0)
        DetectIsdataatFree(idad);
    return ret;
}

/**
 * \brief this function will free memory associated with DetectIsdataatData
 *
 * \param idad pointer to DetectIsdataatData
 */
void DetectIsdataatFree(void *ptr)
{
    DetectIsdataatData *idad = (DetectIsdataatData *)ptr;
    SCFree(idad);
}


#ifdef UNITTESTS
static int g_dce_stub_data_buffer_id = 0;

/**
 * \test DetectIsdataatTestParse01 is a test to make sure that we return a correct IsdataatData structure
 *  when given valid isdataat opt
 */
int DetectIsdataatTestParse01 (void)
{
    int result = 0;
    DetectIsdataatData *idad = NULL;
    idad = DetectIsdataatParse("30 ", NULL);
    if (idad != NULL) {
        DetectIsdataatFree(idad);
        result = 1;
    }

    return result;
}

/**
 * \test DetectIsdataatTestParse02 is a test to make sure that we return a correct IsdataatData structure
 *  when given valid isdataat opt
 */
int DetectIsdataatTestParse02 (void)
{
    int result = 0;
    DetectIsdataatData *idad = NULL;
    idad = DetectIsdataatParse("30 , relative", NULL);
    if (idad != NULL && idad->flags & ISDATAAT_RELATIVE && !(idad->flags & ISDATAAT_RAWBYTES)) {
        DetectIsdataatFree(idad);
        result = 1;
    }

    return result;
}

/**
 * \test DetectIsdataatTestParse03 is a test to make sure that we return a correct IsdataatData structure
 *  when given valid isdataat opt
 */
int DetectIsdataatTestParse03 (void)
{
    int result = 0;
    DetectIsdataatData *idad = NULL;
    idad = DetectIsdataatParse("30,relative, rawbytes ", NULL);
    if (idad != NULL && idad->flags & ISDATAAT_RELATIVE && idad->flags & ISDATAAT_RAWBYTES) {
        DetectIsdataatFree(idad);
        result = 1;
    }

    return result;
}

/**
 * \test Test isdataat option for dce sig.
 */
int DetectIsdataatTestParse04(void)
{
    Signature *s = SigAlloc();
    int result = 1;

    s->alproto = ALPROTO_DCERPC;

    result &= (DetectIsdataatSetup(NULL, s, "30") == 0);
    result &= (s->sm_lists[g_dce_stub_data_buffer_id] == NULL && s->sm_lists[DETECT_SM_LIST_PMATCH] != NULL);
    SigFree(s);

    s = SigAlloc();
    s->alproto = ALPROTO_DCERPC;
    /* failure since we have no preceding content/pcre/bytejump */
    result &= (DetectIsdataatSetup(NULL, s, "30,relative") == 0);
    result &= (s->sm_lists[g_dce_stub_data_buffer_id] == NULL && s->sm_lists[DETECT_SM_LIST_PMATCH] != NULL);

    SigFree(s);

    return result;
}

/**
 * \test Test isdataat option for dce sig.
 */
int DetectIsdataatTestParse05(void)
{
    DetectEngineCtx *de_ctx = NULL;
    int result = 1;
    Signature *s = NULL;
    DetectIsdataatData *data = NULL;

    de_ctx = DetectEngineCtxInit();
    if (de_ctx == NULL)
        goto end;

    de_ctx->flags |= DE_QUIET;
    de_ctx->sig_list = SigInit(de_ctx, "alert tcp any any -> any any "
                               "(msg:\"Testing bytejump_body\"; "
                               "dce_iface:3919286a-b10c-11d0-9ba8-00c04fd92ef5; "
                               "dce_stub_data; "
                               "content:\"one\"; distance:0; "
                               "isdataat:4,relative; sid:1;)");
    if (de_ctx->sig_list == NULL) {
        result = 0;
        goto end;
    }
    s = de_ctx->sig_list;
    if (s->sm_lists_tail[g_dce_stub_data_buffer_id] == NULL) {
        result = 0;
        goto end;
    }
    result &= (s->sm_lists_tail[g_dce_stub_data_buffer_id]->type == DETECT_ISDATAAT);
    data = (DetectIsdataatData *)s->sm_lists_tail[g_dce_stub_data_buffer_id]->ctx;
    if ( !(data->flags & ISDATAAT_RELATIVE) ||
         (data->flags & ISDATAAT_RAWBYTES) ) {
        result = 0;
        goto end;
    }

    s->next = SigInit(de_ctx, "alert tcp any any -> any any "
                      "(msg:\"Testing bytejump_body\"; "
                      "dce_iface:3919286a-b10c-11d0-9ba8-00c04fd92ef5; "
                      "dce_stub_data; "
                      "content:\"one\"; distance:0; "
                      "isdataat:4,relative; sid:1;)");
    if (s->next == NULL) {
        result = 0;
        goto end;
    }
    s = s->next;
    if (s->sm_lists_tail[g_dce_stub_data_buffer_id] == NULL) {
        result = 0;
        goto end;
    }
    result &= (s->sm_lists_tail[g_dce_stub_data_buffer_id]->type == DETECT_ISDATAAT);
    data = (DetectIsdataatData *)s->sm_lists_tail[g_dce_stub_data_buffer_id]->ctx;
    if ( !(data->flags & ISDATAAT_RELATIVE) ||
         (data->flags & ISDATAAT_RAWBYTES) ) {
        result = 0;
        goto end;
    }

    s->next = SigInit(de_ctx, "alert tcp any any -> any any "
                      "(msg:\"Testing bytejump_body\"; "
                      "dce_iface:3919286a-b10c-11d0-9ba8-00c04fd92ef5; "
                      "dce_stub_data; "
                      "content:\"one\"; distance:0; "
                      "isdataat:4,relative,rawbytes; sid:1;)");
    if (s->next == NULL) {
        result = 0;
        goto end;
    }
    s = s->next;
    if (s->sm_lists_tail[g_dce_stub_data_buffer_id] == NULL) {
        result = 0;
        goto end;
    }
    result &= (s->sm_lists_tail[g_dce_stub_data_buffer_id]->type == DETECT_ISDATAAT);
    data = (DetectIsdataatData *)s->sm_lists_tail[g_dce_stub_data_buffer_id]->ctx;
    if ( !(data->flags & ISDATAAT_RELATIVE) ||
         !(data->flags & ISDATAAT_RAWBYTES) ) {
        result = 0;
        goto end;
    }

    s->next = SigInit(de_ctx, "alert tcp any any -> any any "
                      "(msg:\"Testing bytejump_body\"; "
                      "content:\"one\"; isdataat:4,relative,rawbytes; sid:1;)");
    if (s->next == NULL) {
        result = 0;
        goto end;
    }
    s = s->next;
    if (s->sm_lists_tail[g_dce_stub_data_buffer_id] != NULL) {
        result = 0;
        goto end;
    }

 end:
    SigGroupCleanup(de_ctx);
    SigCleanSignatures(de_ctx);
    DetectEngineCtxFree(de_ctx);

    return result;
}

int DetectIsdataatTestParse06(void)
{
    DetectEngineCtx *de_ctx = NULL;
    int result = 0;
    Signature *s = NULL;
    DetectIsdataatData *data = NULL;

    de_ctx = DetectEngineCtxInit();
    if (de_ctx == NULL)
        goto end;

    de_ctx->flags |= DE_QUIET;
    de_ctx->sig_list = SigInit(de_ctx, "alert tcp any any -> any any "
                               "(msg:\"Testing bytejump_body\"; "
                               "content:\"one\"; "
                               "isdataat:!4,relative; sid:1;)");
    if (de_ctx->sig_list == NULL) {
        goto end;
    }

    s = de_ctx->sig_list;
    if (s->sm_lists_tail[DETECT_SM_LIST_PMATCH] == NULL) {
        goto end;
    }

    result = 1;

    result &= (s->sm_lists_tail[DETECT_SM_LIST_PMATCH]->type == DETECT_ISDATAAT);
    data = (DetectIsdataatData *)s->sm_lists_tail[DETECT_SM_LIST_PMATCH]->ctx;
    if ( !(data->flags & ISDATAAT_RELATIVE) ||
         (data->flags & ISDATAAT_RAWBYTES) ||
         !(data->flags & ISDATAAT_NEGATED) ) {
        result = 0;
        goto end;
    }

 end:
    SigGroupCleanup(de_ctx);
    SigCleanSignatures(de_ctx);
    DetectEngineCtxFree(de_ctx);

    return result;
}

/**
 * \test DetectIsdataatTestPacket01 is a test to check matches of
 * isdataat, and isdataat relative
 */
int DetectIsdataatTestPacket01 (void)
{
    int result = 0;
    uint8_t *buf = (uint8_t *)"Hi all!";
    uint16_t buflen = strlen((char *)buf);
    Packet *p[3];
    p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
    p[1] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_UDP);
    p[2] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_ICMP);

    if (p[0] == NULL || p[1] == NULL ||p[2] == NULL)
        goto end;

    char *sigs[5];
    sigs[0]= "alert ip any any -> any any (msg:\"Testing window 1\"; isdataat:6; sid:1;)";
    sigs[1]= "alert ip any any -> any any (msg:\"Testing window 2\"; content:\"all\"; isdataat:1, relative; isdataat:6; sid:2;)";
    sigs[2]= "alert ip any any -> any any (msg:\"Testing window 3\"; isdataat:8; sid:3;)";
    sigs[3]= "alert ip any any -> any any (msg:\"Testing window 4\"; content:\"Hi\"; isdataat:5, relative; sid:4;)";
    sigs[4]= "alert ip any any -> any any (msg:\"Testing window 4\"; content:\"Hi\"; isdataat:6, relative; sid:5;)";

    uint32_t sid[5] = {1, 2, 3, 4, 5};

    uint32_t results[3][5] = {
                              /* packet 0 match sid 1 but should not match sid 2 */
                              {1, 1, 0, 1, 0},
                              /* packet 1 should not match */
                              {1, 1, 0, 1, 0},
                              /* packet 2 should not match */
                              {1, 1, 0, 1, 0} };

    result = UTHGenericTest(p, 3, sigs, sid, (uint32_t *) results, 5);

    UTHFreePackets(p, 3);
end:
    return result;
}

/**
 * \test DetectIsdataatTestPacket02 is a test to check matches of
 * isdataat, and isdataat relative works if the previous keyword is pcre
 * (bug 144)
 */
int DetectIsdataatTestPacket02 (void)
{
    int result = 0;
    uint8_t *buf = (uint8_t *)"GET /AllWorkAndNoPlayMakesWillADullBoy HTTP/1.0"
                    "User-Agent: Wget/1.11.4"
                    "Accept: */*"
                    "Host: www.google.com"
                    "Connection: Keep-Alive"
                    "Date: Mon, 04 Jan 2010 17:29:39 GMT";
    uint16_t buflen = strlen((char *)buf);
    Packet *p;
    p = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);

    if (p == NULL)
        goto end;

    char sig[] = "alert tcp any any -> any any (msg:\"pcre with"
            " isdataat + relative\"; pcre:\"/A(ll|pp)WorkAndNoPlayMakesWillA"
            "DullBoy/\"; isdataat:96,relative; sid:1;)";

    result = UTHPacketMatchSig(p, sig);

    UTHFreePacket(p);
end:
    return result;
}

/**
 * \test DetectIsdataatTestPacket03 is a test to check matches of
 * isdataat, and isdataat relative works if the previous keyword is byte_jump
 * (bug 146)
 */
int DetectIsdataatTestPacket03 (void)
{
    int result = 0;
    uint8_t *buf = (uint8_t *)"GET /AllWorkAndNoPlayMakesWillADullBoy HTTP/1.0"
                    "User-Agent: Wget/1.11.4"
                    "Accept: */*"
                    "Host: www.google.com"
                    "Connection: Keep-Alive"
                    "Date: Mon, 04 Jan 2010 17:29:39 GMT";
    uint16_t buflen = strlen((char *)buf);
    Packet *p;
    p = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);

    if (p == NULL)
        goto end;

    char sig[] = "alert tcp any any -> any any (msg:\"byte_jump match = 0 "
    "with distance content HTTP/1. relative against HTTP/1.0\"; byte_jump:1,"
    "46,string,dec; isdataat:87,relative; sid:109; rev:1;)";

    result = UTHPacketMatchSig(p, sig);

    UTHFreePacket(p);
end:
    return result;
}
#endif

/**
 * \brief this function registers unit tests for DetectIsdataat
 */
void DetectIsdataatRegisterTests(void)
{
#ifdef UNITTESTS
    g_dce_stub_data_buffer_id = DetectBufferTypeGetByName("dce_stub_data");

    UtRegisterTest("DetectIsdataatTestParse01", DetectIsdataatTestParse01);
    UtRegisterTest("DetectIsdataatTestParse02", DetectIsdataatTestParse02);
    UtRegisterTest("DetectIsdataatTestParse03", DetectIsdataatTestParse03);
    UtRegisterTest("DetectIsdataatTestParse04", DetectIsdataatTestParse04);
    UtRegisterTest("DetectIsdataatTestParse05", DetectIsdataatTestParse05);
    UtRegisterTest("DetectIsdataatTestParse06", DetectIsdataatTestParse06);

    UtRegisterTest("DetectIsdataatTestPacket01", DetectIsdataatTestPacket01);
    UtRegisterTest("DetectIsdataatTestPacket02", DetectIsdataatTestPacket02);
    UtRegisterTest("DetectIsdataatTestPacket03", DetectIsdataatTestPacket03);
#endif
}